By the 1850s, the North and South viewed each other as regions conspiring against the liberties of one another. Northerners saw in the expansion of slavery west the presence of a slave power conspiracy that might one day try to re-establish the institution in the North. Southerners saw the gradual elimination of slavery in the North and calls for the government to use its power to restrict slavery as a threat to the survival of the institution. The soil itself came to be viewed as slave or free, and it would take four years of war to decide which way it would ultimately turn.

Slavery was ultimately abolished by the Emancipation Proclamation on January 1, 1863, though technically not in those Confederate areas under Union control. The passage of the 13th Amendment in 1865 marks the institution's final and total abolition.